Throw on broken links, anchors and duplicate routes in CI build

docusaurus.config.ts

@@ -13,8 +13,10 @@ const config: Config = {
   tagline: 'The Free Software Media System',
   url: 'https://jellyfin.org',
   baseUrl: '/',
-  onBrokenLinks: 'warn',
-  onBrokenMarkdownLinks: 'warn',
+  onBrokenAnchors: process.env.CI ? 'throw' : 'warn',
+  onBrokenLinks: process.env.CI ? 'throw' : 'warn',
+  onBrokenMarkdownLinks: process.env.CI ? 'throw' : 'warn',
+  onDuplicateRoutes: process.env.CI ? 'throw' : 'warn',
   favicon: 'images/favicon.ico',
   organizationName: 'jellyfin',
   projectName: 'jellyfin.org',